This invention relates to a sheet transfer device and more specifically to a gripper belt transfer device.
In handling of sheet materials, particularly in the book printing and photographic industry a common method of transferring sheets is by means of a conveyor chain upon which one or more grippers are mounted. The grippers fasten on the edge of the sheet of material and transport it as the chain moves along between one or more pulley or gear wheels. Representative examples of such devices are disclosed in U.S. Pat. Nos. 2,025,371 (Beidler); 3,966,196 (Simeth) and 3,633,903 (Foster).
The gripper chains may be actuated by contact with the edge of the sheet to be transferred (Beidler) or may be actuated by some other means. Photo-optic sensors may be used to control the operation of the machine, as shown in the Foster patent. In all of these devices, however, the sheet which is being transferred is required to have a certain degree of stiffness in order to trip the chain drive actuator. The chains are metallic and therefore require oiling, rendering them unsuitable for use in the fabric industry where such oil would spoil the fabric. Also, because of the greater mass of such metallic transfer devices, their response time is far too slow to meet all transfer needs within the garment manufacturing industry which require a high speed response. There is further the problem that chain-transfer devices which must necessarily be exposed to some degree, are unsafe for mechanically unsophisticated sewing machine operators.